Metronidazole-resistant trichomoniasis: Two Canadian cases

Abstract

Metronidazole-resistant trichomoniasis is a health burden for patients, and limited access to susceptibility testing and treatment is a challenge for Canadian clinicians. These cases emphasize the burden of metronidazole resistance in our population. Herein we describe two cases of metronidazole-resistant trichomoniasis. In one case, a patient underwent five courses of therapy to treat a persistent Trichomonas vaginalis infection. International culture and susceptibility testing revealed resistance to metronidazole and susceptibility to tinidazole. The patient was subsequently lost to follow-up. In another case, a patient was treated with six courses of therapy before their infection had cleared. International culture and susceptibility testing indicated resistance to metronidazole and intermediate resistance to tinidazole. In both cases, metronidazole treatment, either alone or in addition to another therapy, was attempted an average of 3.5 times in escalating dose regimens before switching to tinidazole. Tinidazole proved to be an effective second-line therapy when tolerated by the patient. Until susceptibility testing is available in Canada, clinicians should be aware of access to international susceptibility testing of T. vaginalis to appropriately identify metronidazole-resistant cases and make timely and informed decisions regarding treatment.